3-[(Acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid sodium salt → 3-[(Acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid 2-amino-3-methylbutyryloxymethyl ester

Participants

Reaction Steps

A suspension of 5 grams of 3-[(acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid sodium salt and 8.5 grams of N-tert-butoxycarbonyl-L-valine chloromethyl ester, which is prepared by the general procedure described in W. German Offen. No. 2,236,620, are mixed in 100 ml of dimethyl formamide and stirred for 72 hours. The mixture is diluted with ethyl acetate, washed with water with aqueous bicarbonate and again with water. The organic layer is dried over magnesium sulfate, filtered, and evaporated to dryness to give 3-[(acetyloxy)-methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2carboxylic acid N-tert-butoxycarbonyl-2-amino-3-methylbutyryloxymethyl ester from which the amine protecting group is removed by standard procedures to give the title product.

Provenance & Evidence